Agricultural implements generally include various fluid-driven actuators, such as hydraulic cylinders, for adjusting the relative positioning between certain components of the implement. For example, actuators may be used to adjust the positions of ground-engaging tools, such as a gang of discs, relative to a frame of the implement. Specifically, the actuators may move the ground-engaging tools between an operating position, where the ground-engaging tools are positioned to engage the soil, and a non-operating position, where the ground-engaging tools are lifted up to permit storage and/or transportation on a road.
Several of the actuators on the implement may be fluidly coupled together in series so as to be operated by a single fluid power source and control valve. In such circuit configuration, each actuator, when properly designed, extends and retracts in a generally synchronized manner. However, the synchronization of the actuators is not exact due to the presence of air in the circuit and/or leakage of fluid past pistons of the actuators.
Rephasing ports may be used to correct the synchronization of the actuators in series when leakage occurs. Specifically, rephasing ports are formed in a cylinder of each actuator to permit the actuators to fully extend and/or fully retract. During operation of each actuator in the series, the corresponding piston must slide past the rephasing port twice per stroke cycle. Contact with the edges of the rephasing port often results in excessive wear occurring to the seals coupled to the corresponding piston. Reducing the size of the rephasing ports reduces the wear on the seals, but also increases the time necessary to rephase the circuit. Furthermore, using a harder seal may reduce wear caused by contact with the rephasing ports, but harder seals do not seal as well as softer seals, thereby resulting in increased leakage past the piston.
Accordingly, an improved piston assembly with a valve for use in rephasing a fluid-driven actuator would be welcomed in the technology.